Silicon nitride

About: Silicon nitride is a research topic. Over the lifetime, 32678 publications have been published within this topic receiving 413599 citations. The topic is also known as: N₄Si₃.

A novel fiber-reinforced polyethylene composite with added silicon nitride particles for enhanced thermal conductivity

Abstract: A novel thermally conductive plastic composite was prepared from a mixture of silicon nitride (Si 3 N 4 ) filler particles and an ultrahigh molecular weight polyethylene–linear low density polyethylene blend. The effects of Si 3 N 4 particle sizes, concentration, and dispersion on the thermal conductivity and relevant dielectric properties were investigated. With proper fabrication the Si 3 N 4 particles could form a continuously connected dispersion that acted as the dominant thermally conductive pathway through the plastic matrix. By adding 0–20% Si 3 N 4 filler particles, the composite thermal conductivity was increased from 0.2 to ∼1.0 W m −1 K −1 . Also, the composite thermal conductivity was further enhanced to 1.8 W m −1 K −1 by decreasing the Si 3 N 4 particle sizes from 35, 3 and 0.2 μm, and using coupling agent, for the composites with higher filler content. Alumina short fibers were then added to improve the overall composite toughness and strength. Optimum thermal, dielectric and mechanical properties were obtained for a fiber-reinforced polyethylene composite with 20% total alumina–Si 3 N 4 (0.2 μm size) filler particles.

Surface passivation of silicon solar cells using plasma-enhanced chemical-vapour-deposited SiN films and thin thermal SiO2/plasma SiN stacks

Abstract: Two different techniques for the electronic surface passivation of silicon solar cells, the plasma-enhanced chemical vapour deposition of silicon nitride (SiN) and the fabrication of thin thermal silicon oxide/plasma SiN stack structures, are investigated. It is demonstrated that, despite their low thermal budget, both techniques are capable of giving an outstanding surface passivation quality on the low-resistivity (∼1 � cm) p-Si base as well as on n + -diffused solar cell emitters with the oxide/nitride stacks showing a much better thermal stability. Both techniques are then applied to fabricate frontand rear-passivated silicon solar cells. Open-circuit voltages in the vicinity of 670 mV are obtained with both passivation techniques on float-zone single-crystalline silicon wafers, demonstrating the outstanding surface passivation quality of the applied passivation schemes on real devices. All-SiN passivated multicrystalline silicon solar cells achieve an open-circuit voltage of 655 mV, which is amongst the highest open-circuit voltages attained on this kind of substrate material. The high open-circuit voltage of the multicrystalline silicon solar cells results not only from the excellent degree of surface passivation but also from the ability of the cell fabrication to maintain a relatively high bulk lifetime (>20 µs) due to the low thermal budget of the surface passivation process.

Method for low temperature bonding and bonded structure

Abstract: A method for bonding at low or room temperature includes steps of surface cleaning and activation by cleaning or etching. The method may also include removing by-products of interface polymerization to prevent a reverse polymerization reaction to allow room temperature chemical bonding of materials such as silicon, silicon nitride and SiO2. The surfaces to be bonded are polished to a high degree of smoothness and planarity. VSE may use reactive ion etching or wet etching to slightly etch the surfaces being bonded. The surface roughness and planarity are not degraded and may be enhanced by the VSE process. The etched surfaces may be rinsed in solutions such as ammonium hydroxide or ammonium fluoride to promote the formation of desired bonding species on the surfaces.

Synthesis of Porous Silicon Nitride with Unidirectionally Aligned Channels Using Freeze-Drying Process

Abstract: Porous silicon nitride with macroscopically aligned channels was synthesized using a freeze-drying process. Freezing of a water-based slurry of silicon nitride was done while unidirectionally controlling the growth direction of the ice. Pores were generated subsequently by sublimation of the columnar ice during freeze-drying. By sintering this green body, a porous silicon nitride with high porosity (over 50%) was obtained and its porosity was controllable by the slurry concentration. The porous Si 3 N 4 had a unique microstructure, where macroscopically aligned open pores contained fibrous grains protruding from the internal walls of the Si 3 N 4 matrix. It is hypothesized that vapor/solid phase reactions were important to the formation mechanism of the fibrous grains.

Monolithic nanofluid sieving structures for DNA manipulation

Abstract: A new technique for fabricating two-dimensional and three-dimensional fluid microchannels for molecular studies includes fabricating a monolithic unit using planar processing techniques adapted from semiconductor electronics fabrication. A fluid gap between a floor layer (12) and a ceiling layer (20) is provided by an intermediate patterned sacrificial layer (14) which is removed by a wet chemical etch. The process may be used to produce a structure such as a filter or artificial gel by using Electron beam lithography to define a square array of 100 nm holes (30) in the sacrificial layer. CVD silicon nitride (54) is applied over the sacrificial layer and enters the array of holes to produce closely spaced pillars. The sacrificial layer can be removed with a wet chemical etch through access holes in the ceiling layer, after which the access holes are sealed with VLTO silicon dioxide (64).